A 30 ky child running at 7 m/s jumps onto a 10 kg sled which was initially at rest. What will be the

A 61.6 turns circular coil with radius 4.44 cm and resistance 2.34 Ω is placed in a magnetic field directed perpendicular to the

Setler [38]

Answer:

Induced emf is 0.324 V

Explanation:

We have,

Number of turns, n = 61.6

Radius of circular coil, r = 4.44 cm

Resistance of coil, R = 2.34 Ω

The magnitude of the magnetic field varies in time according to the expression :

$B=a_1t+a_2t^2$

$a_1=0.0411\\\\a_2=0.044$

The magnitude of the induced emf in the coil is given by :

$\epsilon=\dfrac{d\phi}{dt}\\\\\epsilon=\dfrac{d(NBA)}{dt}\\\\\epsilon=NA\dfrac{dB}{dt}$

$\epsilon=\pi r^2\dfrac{dB}{dt}$

At t = 9.21 s,

$\dfrac{dB}{dt}=(0.0411+2\times 0.044 \times 9.21)\\\\\dfrac{dB}{dt}=0.851\ T/s$

$\epsilon=61.6\times \pi \times (4.44 \times 10^{-2})^2\times 0.851$

$\epsilon=5.27\times 10^{-3}\ V$

So, the magnitude of the induced emf in the coil is 0.324 V

5 0

4 years ago

Which set of terms represent mechanical waves?

Helga [31]

Energy that transfers through the medium

4 0

3 years ago

A 68.0-kg person jumps from rest off a 2.20-m-high tower straight down into the water. Neglect air resistance during the descent

Margarita [4]

Answer:

$F= 1333.767\,N$

Explanation:

The velocity of the swimmer just before touching the water is:

$v = -\sqrt{2\cdot (9.807\,\frac{m}{s^{2}} )\cdot (2.20\,m)}$

$v \approx 6.569\,\frac{m}{s}$

The average force exerted on the diver by the water is determined by the use of the Principle of Energy Conservation and the Work-Energy Theorem:

$(68\,kg)\cdot (9.807\,\frac{m}{s^{2}})\cdot (2.20\,m) +\frac{1}{2}\cdot (68\,kg)\cdot (6.569\,\frac{m}{s} )^{2}-F\cdot(2.20\,m) = 0\,J$

$F= 1333.767\,N$

6 0

3 years ago

Read 2 more answers

A person sits on a freely spinning lab stool that has no friction in its axle. When this person extends her arms, A. her moment

Andrei [34K]

Answer:

C. her moment of inertia increases and her angular speed decreases

D. her moment of inertia increases and her angular speed decreases

Explanation:

The moment of inertia of a body is the sum of the products of an increment of mass and the square of its distance from the center of rotation. When a spinning person extends her arms, part of her mass increases its distance from the center of rotation, so increases the moment of inertia.

The kinetic energy of a spinning body is jointly proportional to the moment of inertia and the square of the angular speed. Hence an increase in moment of inertia will result in a decrease in angular speed unless there is a change in the rotational kinetic energy.

This effect is used by figure skaters to increase their spin rate by drawing their arms and legs closer to the axis of rotation. Similarly, they can slow the spin by extending arms and legs.

When the person extends her arms, her moment of inertia increases and her angular speed decreases.

_____

<em>Note to those looking for a letter answer</em>

Both choices C and D have identical (correct) wording the way the problem is presented here. You will need to check carefully the wording in any problem you may think is similar.

3 0

4 years ago

What happened to the kelp forest when the otter was hunted to near extinction?

never [62]

Answer: Sea otter is the pioneer species in the kelp forest as it regulates and controls the population of other species in the kelp forest.

Explanation:

If sea otters are hunted and their population is brought to extinction then this will cause major harm the ecosystem of the kelp forest and it will disturb the ecological balance in the kelp forest. The herbivorous animals consumed by the sea otters will increase in population and they will consume a lot of vegetation in the forest. The kelp forest which forms the coastline will not remain effective in providing protection against the storms to the neighboring areas.

7 0

3 years ago